This plugin preserves formatting of code for display by preventing its modification by WordPress and other plugins while also retaining whitespace.

NOTE: Use of the visual text editor will pose problems as it can mangle your intent in terms of code tags. I strongly suggest you not use the visual editor in conjunction with this plugin as I have taken no effort to make the two compatible.

Notes:

Basically, you can just paste code into code, pre, and/or other tags you additionally specify and this plugin will:

Prevent WordPress from HTML-encoding text (i.e. single- and double-quotes will not become curly; "--" and "---" will not become en dash and em dash, respectively; "..." will not become a horizontal ellipsis, etc)

Prevent most other plugins from modifying preserved code

Prevent shortcodes from being processed

Optionally preserve whitespace (in a variety of methods)

Optionally preserve code added in comments

Keep these things in mind:

ALL embedded HTML tags and HTML entities will be rendered as text to browsers, appearing exactly as you wrote them (including any br tags).